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By Dave Kelly

9-5 Kelly artIt’s a simple fact: When it comes to ponds and watergardens, leaks happen – and they can be devilishly hard to find and repair.

To do right by the plants and fish that inhabit these watershapes, you need to understand a few basic principles of leak detection and be well versed in the sorts of fixes that may be required.

Before we get there, however, it’s important to recognize that leaks are not the only factor that can cause a pond’s water level to drop. In fact, evaporation is actually a more common issue than leakage, with the degree of water loss depending on location, the time of year and the degree to which the pond is exposed to direct sunlight.


When water evaporates, it literally turns to vapor and escapes from the surface of any watershape. How rapidly can this occur? Well, ponds located in areas of the country with moderate temperatures and high humidity can expect to lose an inch or so per week during the spring and summer, with some likely being replaced by rain. But if the pond is in an area with high temperatures and low humidity (Phoenix, for example), it’s possible to see three or more inches of evaporation within a week.

The activity level and size of a pond’s waterfall system is an additive factor in evaporation. Regardless of the climate, a 24-square-foot pond (in surface area) with a 20-foot-long stream featuring five feet of cascading waterfalls may lose two inches or more in a single day, simply because the splashing and moving water exposes a greater evaporative surface to the air than does the still water in a pond.

Lots of times, in other words, an apparent leak will actually turn out to be evaporation.

And there’s another possibility: If you fill the pond one evening and arrive the next morning to find the water down by six inches, it might be that a family of bears stopped by overnight to bathe and slake a considerable thirst. (Seriously, that can be a factor if there are large mammals in the area.) More likely, however, there’s a leak, and not a small one.


Any hunt for leaks should always start with a close look for any low edges. In fact, settling at the edges is the most common of all causes of leaks, especially if the pond/stream installation is relatively new.

Typically, these leaking edges are found in and around the stream and waterfall system. These areas are usually built up during construction using spoils from the excavation of the pond, and it’s quite possible that these sections will settle a bit, especially after a few rainfalls.

But this doesn’t mean the inspection shouldn’t be thorough. Indeed, I strongly recommend a careful look at the entire perimeter of the pond as well, because water escaping at any point in the system will collect in low spots and anywhere else the soil has been disturbed. This can lead to saturation and settling in areas well away from the original leak and may cause additional leaks. So even if you’ve found a low edge up by the waterfall, keep looking for wet mulch or gravel or any muddy areas around the perimeter of the pond: If settling has occurred and you spot another leak, all you have to do is lift the liner up and push some soil under it in order to raise the edge.

Another common problem is splash-out from the stream or waterfall system. This can develop if rocks shift and the stream moves slightly out of its desired course. The fix is simple: Just reposition or reorient a few of the rocks within and around your waterfall to redirect the flow and channel the splash where it should be focused. Once again, problem solved.

If major settling has occurred, however, it may be necessary to dismantle a portion of the edge, lift the liner, backfill the area with additional soil and compact it into place. This involves a good bit of effort, but it’s a sure way to raise the edge of the liner above the water level.


While checking edges and observing any splash issues, it also pays to keep an eye out for any obstructions that might have developed (or might be developing) along the course of the stream and waterfall. Many times, shifted rocks or unrestrained plant growth or even a nasty algae bloom will clog certain passages or will restrict flow into the pond’s circulation system, and the result can lead to a diversion of water over the edge of the liner.

There’s another easy, commonsense remedy here: Just clear away the clogs, keep aquatic plants trimmed and don’t let algae get the upper hand.

All in all, the inspection described here so far involves about 15 minutes of careful hunting for problems and problem areas. By and large, such a hunt will help in resolving most common issues – but sometimes there’s more going on than meets the eye. You’ll know something’s up if the water level continues to drop more rapidly than evaporation would explain.

If this is the case, fill the pond to the appropriate level and turn off the pump. After 24 hours, check the water level: If it hasn’t dropped noticeably, it’s safe to assume that the leak is not in the pond and it’s time to check the pipes, fittings and pump connections for leaks.

If you find no problems with the plumbing, check the skimmer (if the pond has one). Move a few rocks away from the front of the opening and slide your hand behind the liner, feeling for wet soil around the back side of the opening. If the soil is saturated, the faceplate may be the source of the leak. To fix it, just remove the faceplate, clean all of the old silicone off the liner, and (referring to the instruction manual for proper procedures) simply reseal and reset the faceplate on the skimmer.

But if the water level in the pond drops overnight, you know you have an as-yet-undetected leak in the pond itself.

To find the leak, allow the water level to keep on dropping. When it stops, you’ll know approximately the level at which the leak is occurring and can concentrate your search at that level. Now the fun begins: Start by removing any rocks around the entire perimeter above the level where the water stopped disappearing. With all that done, it’s time to check the liner for any sort of puncture, fracture or tear. Once you’ve found the spot, patch it with a liner patch, then replace the rocks and refill the pond.

Leaking ponds are no fun, but if you enter the repair process with a sensible, systematic plan and stick to it, you can rest assured the problem will be addressed – and the fish and plants will be happy once again.


Dave Kelly is Vice President of Product Development for Aquascape, a waterfeature design and installation company headquartered in St. Charles, Ill. For more information, go to

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